On Thu, 2003-03-06 at 15:00, Andreas Pflug wrote:
> How can I detect whether a column was changed by an update command
> inside a trigger?
>
> create table test(a int, b int, c int, primary key(a))
>
> b and c should be updated inside an update trigger if not modified by
> the statement itself
>
> 1) update test set a=0 -> trigger does its work
> 2) update test set a=0, b=1, c=2 -> trigger does nothing
> 3) update test set a=0, b=b, c=c -> trigger does nothing, but content of
> a and b dont change either although touched
>
> What I'm looking for is something like
> IF NOT COLUMN_TOUCHED(b) THEN ...
> For MSSQL, this would be coded as IF NOT UPDATE(b) ..
IF NEW.b = OLD.b OR (NEW.b IS NULL AND OLD.b IS NULL) THEN
-- b has not changed
...
END IF;
--
Oliver Elphick Oliver(dot)Elphick(at)lfix(dot)co(dot)uk
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